linux-stable.git/kernel, branch v4.9.307

tracing: Ensure trace buffer is at least 4096 bytes large

2022-03-16T11:49:01+00:00

[ Upstream commit 7acf3a127bb7c65ff39099afd78960e77b2ca5de ]

Booting the kernel with 'trace_buf_size=1' give a warning at
boot during the ftrace selftests:

[    0.892809] Running postponed tracer tests:
[    0.892893] Testing tracer function:
[    0.901899] Callback from call_rcu_tasks_trace() invoked.
[    0.983829] Callback from call_rcu_tasks_rude() invoked.
[    1.072003] .. bad ring buffer .. corrupted trace buffer ..
[    1.091944] Callback from call_rcu_tasks() invoked.
[    1.097695] PASSED
[    1.097701] Testing dynamic ftrace: .. filter failed count=0 ..FAILED!
[    1.353474] ------------[ cut here ]------------
[    1.353478] WARNING: CPU: 0 PID: 1 at kernel/trace/trace.c:1951 run_tracer_selftest+0x13c/0x1b0

Therefore enforce a minimum of 4096 bytes to make the selftest pass.

Link: https://lkml.kernel.org/r/20220214134456.1751749-1-svens@linux.ibm.com

Signed-off-by: Sven Schnelle 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Sasha Levin

x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting

2022-03-11T09:03:31+00:00

commit 44a3918c8245ab10c6c9719dd12e7a8d291980d8 upstream.

With unprivileged eBPF enabled, eIBRS (without retpoline) is vulnerable
to Spectre v2 BHB-based attacks.

When both are enabled, print a warning message and report it in the
'spectre_v2' sysfs vulnerabilities file.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
[fllinden@amazon.com: backported to 4.19]
Signed-off-by: Frank van der Linden 
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix tp_printk option related with tp_printk_stop_on_boot

2022-02-23T10:56:41+00:00

[ Upstream commit 3203ce39ac0b2a57a84382ec184c7d4a0bede175 ]

The kernel parameter "tp_printk_stop_on_boot" starts with "tp_printk" which is
the same as another kernel parameter "tp_printk". If "tp_printk" setup is
called before the "tp_printk_stop_on_boot", it will override the latter
and keep it from being set.

This is similar to other kernel parameter issues, such as:
  Commit 745a600cf1a6 ("um: console: Ignore console= option")
or init/do_mounts.c:45 (setup function of "ro" kernel param)

Fix it by checking for a "_" right after the "tp_printk" and if that
exists do not process the parameter.

Link: https://lkml.kernel.org/r/20220208195421.969326-1-jsyoo5b@gmail.com

Signed-off-by: JaeSang Yoo 
[ Fixed up change log and added space after if condition ]
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Sasha Levin

taskstats: Cleanup the use of task->exit_code

2022-02-23T10:56:40+00:00

commit 1b5a42d9c85f0e731f01c8d1129001fd8531a8a0 upstream.

In the function bacct_add_task the code reading task->exit_code was
introduced in commit f3cef7a99469 ("[PATCH] csa: basic accounting over
taskstats"), and it is not entirely clear what the taskstats interface
is trying to return as only returning the exit_code of the first task
in a process doesn't make a lot of sense.

As best as I can figure the intent is to return task->exit_code after
a task exits.  The field is returned with per task fields, so the
exit_code of the entire process is not wanted.  Only the value of the
first task is returned so this is not a useful way to get the per task
ptrace stop code.  The ordinary case of returning this value is
returning after a task exits, which also precludes use for getting
a ptrace value.

It is common to for the first task of a process to also be the last
task of a process so this field may have done something reasonable by
accident in testing.

Make ac_exitcode a reliable per task value by always returning it for
every exited task.

Setting ac_exitcode in a sensible mannter makes it possible to continue
to provide this value going forward.

Cc: Balbir Singh 
Fixes: f3cef7a99469 ("[PATCH] csa: basic accounting over taskstats")
Link: https://lkml.kernel.org/r/20220103213312.9144-5-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" 
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee 
Signed-off-by: Greg Kroah-Hartman

bpf: Add kconfig knob for disabling unpriv bpf by default

2022-02-16T11:43:54+00:00

commit 08389d888287c3823f80b0216766b71e17f0aba5 upstream.

Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.

This still allows a transition of 2 -> {0,1} through an admin. Similarly,
this also still keeps 1 -> {1} behavior intact, so that once set to permanently
disabled, it cannot be undone aside from a reboot.

We've also added extra2 with max of 2 for the procfs handler, so that an admin
still has a chance to toggle between 0 <-> 2.

Either way, as an additional alternative, applications can make use of CAP_BPF
that we added a while ago.

Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
[fllinden@amazon.com: backported to 4.9]
Signed-off-by: Frank van der Linden 
Signed-off-by: Greg Kroah-Hartman

cgroup-v1: Require capabilities to set release_agent

2022-02-11T07:41:17+00:00

commit 24f6008564183aa120d07c03d9289519c2fe02af upstream.

The cgroup release_agent is called with call_usermodehelper.  The function
call_usermodehelper starts the release_agent with a full set fo capabilities.
Therefore require capabilities when setting the release_agaent.

Reported-by: Tabitha Sable 
Tested-by: Tabitha Sable 
Fixes: 81a6a5cdd2c5 ("Task Control Groups: automatic userspace notification of idle cgroups")
Cc: stable@vger.kernel.org # v2.6.24+
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Tejun Heo 
[mkoutny: Adjust for pre-fs_context, duplicate mount/remount check, drop log messages.]
Acked-by: Michal Koutný 
Signed-off-by: Greg Kroah-Hartman

PM: wakeup: simplify the output logic of pm_show_wakelocks()

2022-02-08T17:15:26+00:00

commit c9d967b2ce40d71e968eb839f36c936b8a9cf1ea upstream.

The buffer handling in pm_show_wakelocks() is tricky, and hopefully
correct.  Ensure it really is correct by using sysfs_emit_at() which
handles all of the tricky string handling logic in a PAGE_SIZE buffer
for us automatically as this is a sysfs file being read from.

Reviewed-by: Lee Jones 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

tracing: Tag trace_percpu_buffer as a percpu pointer

2022-01-11T12:38:11+00:00

commit f28439db470cca8b6b082239314e9fd10bd39034 upstream.

Tag trace_percpu_buffer as a percpu pointer to resolve warnings
reported by sparse:
  /linux/kernel/trace/trace.c:3218:46: warning: incorrect type in initializer (different address spaces)
  /linux/kernel/trace/trace.c:3218:46:    expected void const [noderef] __percpu *__vpp_verify
  /linux/kernel/trace/trace.c:3218:46:    got struct trace_buffer_struct *
  /linux/kernel/trace/trace.c:3234:9: warning: incorrect type in initializer (different address spaces)
  /linux/kernel/trace/trace.c:3234:9:    expected void const [noderef] __percpu *__vpp_verify
  /linux/kernel/trace/trace.c:3234:9:    got int *

Link: https://lkml.kernel.org/r/ebabd3f23101d89cb75671b68b6f819f5edc830b.1640255304.git.naveen.n.rao@linux.vnet.ibm.com

Cc: stable@vger.kernel.org
Reported-by: kernel test robot 
Fixes: 07d777fe8c398 ("tracing: Add percpu buffers for trace_printk()")
Signed-off-by: Naveen N. Rao 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix check for trace_percpu_buffer validity in get_trace_buf()

2022-01-11T12:38:11+00:00

commit 823e670f7ed616d0ce993075c8afe0217885f79d upstream.

With the new osnoise tracer, we are seeing the below splat:
    Kernel attempted to read user page (c7d880000) - exploit attempt? (uid: 0)
    BUG: Unable to handle kernel data access on read at 0xc7d880000
    Faulting instruction address: 0xc0000000002ffa10
    Oops: Kernel access of bad area, sig: 11 [#1]
    LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
    ...
    NIP [c0000000002ffa10] __trace_array_vprintk.part.0+0x70/0x2f0
    LR [c0000000002ff9fc] __trace_array_vprintk.part.0+0x5c/0x2f0
    Call Trace:
    [c0000008bdd73b80] [c0000000001c49cc] put_prev_task_fair+0x3c/0x60 (unreliable)
    [c0000008bdd73be0] [c000000000301430] trace_array_printk_buf+0x70/0x90
    [c0000008bdd73c00] [c0000000003178b0] trace_sched_switch_callback+0x250/0x290
    [c0000008bdd73c90] [c000000000e70d60] __schedule+0x410/0x710
    [c0000008bdd73d40] [c000000000e710c0] schedule+0x60/0x130
    [c0000008bdd73d70] [c000000000030614] interrupt_exit_user_prepare_main+0x264/0x270
    [c0000008bdd73de0] [c000000000030a70] syscall_exit_prepare+0x150/0x180
    [c0000008bdd73e10] [c00000000000c174] system_call_vectored_common+0xf4/0x278

osnoise tracer on ppc64le is triggering osnoise_taint() for negative
duration in get_int_safe_duration() called from
trace_sched_switch_callback()->thread_exit().

The problem though is that the check for a valid trace_percpu_buffer is
incorrect in get_trace_buf(). The check is being done after calculating
the pointer for the current cpu, rather than on the main percpu pointer.
Fix the check to be against trace_percpu_buffer.

Link: https://lkml.kernel.org/r/a920e4272e0b0635cf20c444707cbce1b2c8973d.1640255304.git.naveen.n.rao@linux.vnet.ibm.com

Cc: stable@vger.kernel.org
Fixes: e2ace001176dc9 ("tracing: Choose static tp_printk buffer by explicit nesting count")
Signed-off-by: Naveen N. Rao 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

timekeeping: Really make sure wall_to_monotonic isn't positive

2021-12-22T08:05:14+00:00

commit 4e8c11b6b3f0b6a283e898344f154641eda94266 upstream.

Even after commit e1d7ba873555 ("time: Always make sure wall_to_monotonic
isn't positive") it is still possible to make wall_to_monotonic positive
by running the following code:

    int main(void)
    {
        struct timespec time;

        clock_gettime(CLOCK_MONOTONIC, &time);
        time.tv_nsec = 0;
        clock_settime(CLOCK_REALTIME, &time);
        return 0;
    }

The reason is that the second parameter of timespec64_compare(), ts_delta,
may be unnormalized because the delta is calculated with an open coded
substraction which causes the comparison of tv_sec to yield the wrong
result:

  wall_to_monotonic = { .tv_sec = -10, .tv_nsec =  900000000 }
  ts_delta 	    = { .tv_sec =  -9, .tv_nsec = -900000000 }

That makes timespec64_compare() claim that wall_to_monotonic < ts_delta,
but actually the result should be wall_to_monotonic > ts_delta.

After normalization, the result of timespec64_compare() is correct because
the tv_sec comparison is not longer misleading:

  wall_to_monotonic = { .tv_sec = -10, .tv_nsec =  900000000 }
  ts_delta 	    = { .tv_sec = -10, .tv_nsec =  100000000 }

Use timespec64_sub() to ensure that ts_delta is normalized, which fixes the
issue.

Fixes: e1d7ba873555 ("time: Always make sure wall_to_monotonic isn't positive")
Signed-off-by: Yu Liao 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211213135727.1656662-1-liaoyu15@huawei.com
Signed-off-by: Greg Kroah-Hartman